Investigation of Droplet Ejection Mechanism from Electrode in Multi-Phase AC Arc

Abstract

A multi-phase AC arc has various advantages such as high energy efficiency, large plasma volume and low gas velocity. Therefore, the multi-phase AC arc is suitable to massive powder processing like nanomaterial fabrication processes and innovative in-flight glass melting technology. However, the understanding of discharge behavior of multi-phase AC arc still remains to be improved for the practical use. In particular, electrode erosion is one of the most important issues to be solved. The purpose of this study is to investigate the droplet ejection mechanism of the multi-phase AC arc based on high-speed visualization by the high-speed camera and appropriate band-pass filters system. Obtained results indicated that droplet ejection was involved by variation in current and voltage during an AC cycle. The larger droplets were ejected at only cathodic period and the transition time from the cathodic to anodic AC period. Estimation of forces acting on the molten droplet revealed the electromagnetic force was most important force which leads to the detachment of the droplet from the electrode surface. Smaller droplet on the electrode tip leads to the droplet ejection due to the relatively stronger electromagnetic force than surface tension.